Piaggio P-119

[Shortround6]

The Piaggio 18 cylinder engines were around the same size as a Wright R-3350, although hundreds of pounds lighter.
Using one on a Fiat G.55 or Re.2005 might mean loosing ALL the fuselage guns.

 

[tomo pauk]

Indeed. The guns will probably go in the wings, whether at the roots or utside the prop disc, like it was proposed for the MC.207. The Fiat G.57 was to be powered by a big Fiat's radial.

 

[AMCKen]

I have often wondered why those aircraft like the P-39 and P-63 had the driveshaft running at engine rpm. Would it not have reduced the vibration to have the reduction gear at the engine and then just a thrust-line mover gearbox at the front?

 

[wuzak]

I have often wondered why those aircraft like the P-39 and P-63 had the driveshaft running at engine rpm. Would it not have reduced the vibration to have the reduction gear at the engine and then just a thrust-line mover gearbox at the front?

If you apply the speed reduction at the engine, the drive shaft will have to be bigger and heavier.

The limiting factor for the drive shaft is torque, not power. If the speed is halved the torque is doubled.

The other convenience in running the driveshaft off the end of the crankshaft is that the drive line is lower than if it came off a reduction gear on the motor. Of course you could have it offset to lower the drive line, but then you would need a bigger/stronger gearbox at the front to drive the prop.

 

[swampyankee]

I have often wondered why those aircraft like the P-39 and P-63 had the driveshaft running at engine rpm. Would it not have reduced the vibration to have the reduction gear at the engine and then just a thrust-line mover gearbox at the front?

Since torque is lower at engine rpm, the shaft can be smaller and lighter. I suspect the gearbox could be, too, as the spring (driveshaft) connecting the two vibration sources, the engine and propeller, is less stiff, making it easier for the shaft's fundamental frequencies to be outside the operational rpm band. I'm not going to try an analysis right now; to do that I'd need to spend some quality time with my vibrations books an a computer. A separate design issue is I believe the reason for the mid-engine design (neglecting all the downsides of that decision) was so that a hub-mounted cannon could be installed. This would not be possible if the reduction gearbox was attached to the engine behind the pilot.

 

[wuzak]

As an interesting note, the Griffon for the Rolls-Royce flying test bed had a gear arrangement to drop the driveshaft below the crankshaft. It may have even been geared up so that the driveshaft turned at higher rpm.

 

[wuzak]

I suspect the gearbox could be, too, as the spring (driveshaft) connecting the two vibration sources, the engine and propeller, is less stiff, making it easier for the shaft's fundamental frequencies to be outside the operational rpm band.

Regardless of vibrations, the gearbox could be lighter for higher input rpm because gears are also rated on torque.

 

[johnbr]

 

[Wurger]

 

[Gnomey]

Good shots!

 

[Capt. Vick]

What a great thread!

 

[Zipper730]

Besides the BMW 801's geared fan similar fans were later used on the R-4360

I didn't know that...

On the R-4360 this was supposedly so well done that the rear cylinders row ran cooler than the first.

I'm not sure if that's right -- the R-4360 ran it's first cylinders hotter than the last because the hottest cylinders would face the coldest air, and the rear cylinders would be toasty but it wouldn't matter because the cylinders aren't as hot.

Late model Radial engines are really oil cooled rather than air cooled.

That I didn't know, though your description seems to describe the oil cooler as integrated into the cowling, not the cylinders...

 

[Shortround6]

I'm not sure if that's right -- the R-4360 ran it's first cylinders hotter than the last because the hottest cylinders would face the coldest air, and the rear cylinders would be toasty but it wouldn't matter because the cylinders aren't as hot.

you might want to rethink that.
Please take into consideration that most (all?) display/museum engines ave the sheet metal baffles that guide the air removed so you can see the engines.

whereas an engine in the aircraft is almost invisible even with the cowl removed.

or

Airflow was very carefully worked out to get cool air to each cylinder with close fitting baffles directed the airflow through the fins.
Airflow around the middle/rear cylinders was almost sideways and not limited to getting preheated air that had flowed over the front cylinders.

 

[Zipper730]

you might want to rethink that.

That's what I was told...

Airflow was very carefully worked out to get cool air to each cylinder with close fitting baffles directed the airflow through the fins.

That was supposedly a substantial undertaking...

Airflow around the middle/rear cylinders was almost sideways

Sideways?

 

[johnbr]

 

[Wurger]

 

[johnbr]

The basic concept of the aircraft was based on locating the star engine in the fuselage, behind the pilot, at the center of gravity. Since Piaggio only built star engines, the solution to obtain a device with low aerodynamic resistance was to "mask" the thruster in the central section of the fuselage. Such architecture should also provide excellent maneuverability to the device and allow to concentrate a powerful armament in the nose. This configuration was identical to that of the P-39 Airacobra built in the United States by Bell, which made its first flight in 1938. The Piaggio project, led by Giovanni Casiraghi who had spent 9 years in the United States in the aviation industry , was submitted to Regia Aeronautica on March 18, 1939. However, the priority of the moment being given to the rise of the front-line units, this experimental program took a long time.
The fuel was stored in 2 330 L tanks located in the wings and one 340 L in the fuselage, resulting in a total of 1000 L.

If the prototype was armed with only 2 12.7 mm Breda-SAFAT machine guns located in the nose and pulling through the propeller disc, the standard armament provided for 2 additional 12.7 mm Breda-SAFAT machine guns. and a 20 mm Breda gun.

Piaggio did not receive the order for a prototype, amounting to 2,280,000 lire, on June 2, 1941. The Piaggio factory in Finale Ligure already having a heavy workload, the MM.497 prototype was only completed in the second half of 1942. Ground tests began in November on the site of Villanova d'Albenga, while Nicolò Lana made the first flight on December 19, 1942. The first flight tests immediately showed a problem of overheating. engine, forcing the aircraft to fly with the hood flaps still open. The aerodynamic interference created by the latter was manifested by a tendency of the nose-up device. In addition, the engine could not be pushed at maximum speed because of the vibrations transmitted to the cell. Finally, P.119 was subject to a problem of centering, a difficulty that had also been faced by the fathers of the P-39. During the flight tests, all conducted from the field of Villanova d'Albenga, the various problems mentioned above prevented to determine the performance of the aircraft, particularly with regard to the speed and maximum speed. No firing attempts were made despite the installation of 2 12.7 mm machine guns in the nose.On August 2, 1943, during a landing, the malfunction of the brakes caused a swerving of the aircraft which caused some damage to the propeller and a winged salmon. Although easily repairable, the apparatus remained in the state until the armistice of September 8, 1943, date when the project was purely and simply abandoned.
The Piaggio P.119 was designed as a low-wing monoplane fighter with a fully metallic duralumin structure. The main gear, retractable by rotation towards the fuselage, was completely erased. The tail wheel was swiveling but not retractable. From the cockpit protected by a canopy opening by lateral tilting, the pilot enjoyed an excellent visibility, made possible thanks to the arrangement of the engine just behind the cockpit.
To drive the Piaggio P.1002 three-bladed propeller with a variable pitch of 3.3 m in diameter, the propeller shaft traversed the entire cockpit and nose and attacked the misaligned helical gearbox to accommodate the gun barrel. mm pulling through the hub. The ventral air intake, with a careful aerodynamics, was insufficient, as we saw earlier, to ensure proper cooling of the star engine Piaggio P.XV RC45 18-cylinder installed on the prototype. The air passed through a tunnel located under the cockpit before reaching the cylinder heads and being evacuated by the radially distributed flaps on the flanks of the fuselage, to the right of the trailing edge of the wings. Note that the prototype eventually had to receive a Piaggio P.XV RC15 / 60 equipped with a 2-speed compressor, which was never installed due to cooling problems. For the hypothetical exemplary series, Piaggio thought to move to the P.XV RC50 / 2V or P.XXII 1700 ch at takeoff. But these two engines were still not available at the time of the armistice. Piaggio P.119

 

[johnbr]

 

[Hardrada55]

Should have built the Piaggio P.132 instead.

 

[johnbr]

Data sheet
FEATURES
engine: Piaggio P.XV RC.60
power: 1650 hp at take-off
wingspan: 13.00 m
total length: 13.00 m
total height: 3.00 m
wing surface: mq. 27,80
empty weight: 2,670 kg
weight at maximum load: 4.100 kg
maximum speed (expected): km / h. 640 to 6,800 m
minimum speed: km / h 130
rise time (expected): 7 '15' 'at 6,000 m
maximum tangency: 12.500 m
Rn: 1,500 km
take-off: 250 m
landing: m 300
armament: 2 12.7 mm machine guns in the muzzle
designer: Giovanni Casiraghi
test pilot: Nicolò Lana
first prototype flight: MM. 497 on December 19, 1942